In a super-critical fluid chromatography (SFC) device or a super-critical fluid extraction (SFE) device, a super-critical fluid of over 10 MPa (megapascals), or CO2 in a liquid state is decompressed to atmospheric pressure and vaporized after passing through a back pressure regulator (BPR). In a SFC and a SFE each having a dispensing function, a sample dissolved in, for example, a mixed fluid of CO2 and a modifier, is collected after being passed through a BPR. Since the vaporized CO2 has a volume expanded as many as 400 times, a problem occurs that a fluid flowing out from outlet piping scatters to lose the sample.
In order to solve the problem, a gas-liquid separator is required which separates a gas (CO2) and a liquid (modifier, mainly MeOH) and recovers only a liquid. Such a gas-liquid separator is disclosed in, for example, Patent Documents 1 to 7.
After passing through a column in a SFC or a SFE, targets to be dispensed emerge as a group of chromatograph peaks. Each peak of a group of chromatograph peaks is called a fraction. A large number of fractions (peaks) are adjacently separated with a space in, for example, seconds. The fractions should all be collected.
For the collection of fractions, a fraction collector is used. For example, a fraction collector used in ordinary liquid chromatograph (LC) drips numerous fractions into numerous collection vials spatially arranged (e.g. test tubes etc.) by moving a head with a discharge port in an X-Y direction.
Here, a fraction dispensing method will be described separately in, for example, three types.
A first dispensing method is a method in which gas-liquid separators are provided corresponding to a plurality of gathering vials. This method is disclosed in, for example, Patent Documents 1, 3, and 7. The numerous fractions have flow channels thereof switched by a valve so as to be led to the gathering vials via a gas-liquid separator. Through one gas-liquid separator, only one fraction passes. Accordingly, this method has an advantage that neither an amount of a dead volume nor cross-contamination (for example, individual peaks are broadened to cross with each other) causes a problem. However, commercially available switching valves, for example, have a maximum of six sides, and for dispensing more fractions (target chromatograph peaks to be dispensed), valves should be connected in a plurality of stages to involve problems of an increase in scale of a system and complication of the same.
A second dispensing method is a method of conducting gas-liquid separation within a collection vial. Since this method involves no dead volume, the method has an advantage of having no cross-contamination problem. This method is disclosed in, for example, Patent Document 2. The method disclosed in Patent Document 2 is capable of dispensing numerous fractions by moving a fraction discharging probe to numerous recovery vials spatially arranged similarly to a fraction collector for an LC, without using a switching valve. However, in the method disclosed in Patent Document 2, the recovery vial and a front end of the probe should be attached or detached by moving the front end of the probe in a Z-direction temporally before and after the probe is moved in an X-Y direction. Therefore, the method disclosed in Patent Document 2 is not allowed to dispense fractions during a dead time of attachment and detachment, and has accordingly difficulty in dispensing fractions extremely close to each other.
A third dispensing method is a type having one gas-liquid separator in a flow channel on an upstream side of a fraction collector. Since this method sends only a liquid to the fraction collector, the method is capable of dispensation as in a conventional LC. The method is disclosed in, for example, Patent Documents 4, 6, and 7.
For realizing a device capable of acquiring numerous fractions while ensuring simplicity of a device configuration, the above third dispensing method is considered to be preferable. However, when a tube with an enlarged internal diameter called a dripper is used as in Patent Document 4, a swirling flow is generated in the enlarged internal diameter portion of the tube as shown in Patent Document 5 to cause cross-contamination in which a plurality of fractions temporally close to each other mix with each other. When a swirling flow is generated in the tube, flows go vertically adjacent to each other between a first round and a second round, and between the second round and a third round. It is easily supposed that when numerous fractions come into such a flow, components temporally different from each other mix with each other. A swirling flow disclosed in Patent Document 6 and remains in a porous filter as disclosed in Patent Document 7 also cause cross-contamination.
Additionally, dead volumes in an inner tube as disclosed in Patent Document 4, in a chamber as disclosed in Patent Document 6, in a chamber as disclosed in Patent Document 7, and the like broaden a peak. This also causes cross-contamination. Additionally, a problem of carryover occurs in which a residual component mixes at subsequent dispensation. Such a structure as disclosed, for example, in Patent Document 4, is not preferable, in which a mobile phase passes through an inner wall of a chamber having a large capacity.